Method of making pistons



Nov. 28, 1933. A, A, HANDLER 1,936,598

METHOD OF MAKING PISTONS Filed March 18, 1931 2 Sheets-Sheet 1 gwmantow Nov; 28, 1933. A A, HA DLER 1,936,598

METHOD OF MAKING PISTONS Filed March 18, 1931 2 Sheets-Sheet 2 MM is gwoenkow Patented Nov. 28, 1933 UNITED STATES PATENT OFFICE METHOD OF MAKING PISTONS Application March 18, 1931. Serial No. 523,604

' 9 Claims. (01. 29-15(55) This invention relates to metal working, and particularly to the manufacture of internal combustion engine pistons.

The present invention is an improvement over the invention claimed in my co-pending application, Serial No. 523,602 filed March 18, 1931, and has for its principal object the provision of a process of forming a flange or the like on a tubular member such as the skirt of an internal combustion engine piston. Another object is to construct a piston or the like by an upsetting operation, and to form a flange thereon without altering the metallic structure originally imparted thereto by the upsetting process. Other objects relating to details of the process and economies or" manufacture will appear hereinafter.

in the accompanying drawings:

Fig. l is a view partly in section and partly in elevation illustrating a form of apparatus for carrying out one step of the process,

2 is a similar View with the parts n a different position.

3 is a sectional view of the piston after completion of the first steps of the process.

Fig. 1 is a sectional view of a form of apparatus for performing the final operation.

Figs. 5 and 6 are sectional views of the completed piston.

i'he improved process consists broadly in flowing metal into the form of a piston having an annular external shoulder adjacent the open end by means of an upsetting operation, removing a portion of the metal from the interior of the shoulder, and bending the shoulder inwardly to leave the exterior surface cylindrical and form an inwardly projecting flange at the open end.

In carrying out the process, a slug or billet of metal 10, which may be cast or forged in any suitable shape, is placed in a divided confining die 11, the interior surfaces of which conform to the desired exterior surface of the piston. An annular groove 12 is formed in the die 11 adjacent the open end thereof and is provided with substantially straight sides 13 and 14 disposed at about right angles to each other.

A plunger 15 is then forced into the metal to flow a portion thereof into the form of a skirt, as illustrated in Fig. 2. The plunger 15 is formed with a cylindrical portion 16 having oppositely disposed recesses 1'7 and 18 to form piston pin bosses 19 and 20 on the interior of the piston. Preferably the end face of the plunger is provided with a groove 21 to form a rib 22 on the under side of the piston head. A portion of the metal is forced outwardly along the surface of the die 11 to fill the groove 12 and form an annular external shoulder 23 at the open end of the piston. The cylindrical portion 16 of the plunger terminates in an annular shoulder 24 which may be substantially perpendicular to the 6(1) axis of the plunger, as shown, or may be frustroconical in shape to form an end surface 25 on the piston substantially perpendicular to the outer wall of the shoulder 23on the piston.

The plunger is then withdrawn and the piston 135 is removed from the die 11. The interior surface of the piston is then formed with a groove 26 by a suitable machining operation, so that the contour of the interior surface below the shoulder 23 is similar to the contour of the exterior surface, as shown in Fig. 3. When the plunger is constructed with a fiat abutting shoulder 24, as illustrated in Figs. 1 and 2, the conical end face 25 is preferably formed by a machining op eration or the like.

A sectional core 27 is then assembled in the piston. This core may conveniently be of seven part construction, comprising a central member 28 and six side members 29 disposed thereabout in such a manner that their combined exterior surfaces fit the interior surface of the piston. The end of the core is subjected to pressure by a ram of any suitable type, and the piston is forced through an opening 30 in a drawing die 31. The die permits the passage of the head and the cylindrical por- 35 tion of the skirt of the piston, but upsets the walls of the shoulder 23 inwardly to make the diameter of the external surface of the piston substantially uniform, and to form an inwardlyprojecting annu ar flange 32 on the open end of the piston.

The piston is then given the final machining operations, during which the ring grooves 33 are cut in the head, and the piston pin bosses l9 and 20 are bored as indicated at 34.

The temperature of the slug or billet 10 during the initial upsetting operation may be anything between the ordinary forging temperature and the melting pointof the most fusible eutectic in the alloy, or from about 800 degrees F. to about 960 degrees F. with most aluminum alloys. The ordinary forging temperature is usually the highest temperature which can be safely used without danger of breaking up the object being forged. Since the initial upsetting operation takes place in a confining die, there is little danger of break- 5 ing up the metal, and higher temperatures may 1 be used. The wide range of permissible temperatures obviates the necessity of close control of the preliminary heating of the metal.

It will be evident that the piston produced by this process possesses, particularly in the skirt, a

' relatively fine rather than coarse, metallic structure; resulting from the deforming of the metal during the formation of the skirt and the drawing incident to the formation of the flange. This structure results in improved characteristics, tensile strength and elongation. In an alternate form, in which the piston is upset from a cast slug, the head portion is worked but slightly and the structure thereof more nearly resembles a casting.

A distinct advantage of the present process is its adaptability for use with light metal alloys which are difficult to cast successfully in varying sections without the formation of surface cracks or porosity from internal shrinkage and the like. This is particularly true of high silicon aluminum alloys or similar compositions having a relatively high percentage of hardening or expansion reducing constituents. When worked according to the present process pistons having extremely desirable physical characteristics may be conveniently manufactured Without scrap loss and with but negligible loss from imperfections.

Pistons similar to those produced by the present process are disclosed and claimed in my copending application, Serial No. 525,277 filed March 25, 1931.

Although the foregoing description is necessarily of a detailed character in order that the invention may be fully disclosed, it is to be understood that the specific terminology employed is not to be construed as restrictive or limiting, and it is to be further understood that various modifications may be resorted to without departing from the spirit and scope of the invention as defined in the following claims.

I claim:

1. The process of making pistons comprising upsetting metal into the form of a piston having a head and an externally shouldered skirt, removing metal from the interior of such shoulder, and forcing the shoulder inwardly to form an internal flange on the skirt.

2. The process of making pistons comprising upsetting metal into the form of a piston having a head and a skirt, the skirt having an external annular shoulder adjacent the open end thereof, forming a groove in the interior of the skirt beneath, and conforming in outline to the external shoulder, and drawing the skirt through a die to render the exterior surface substantially cylindrical and form an inwardly extending annular flange at the open end of the piston.

3. The process of forming a flange at an end of a tubular article comprising forming an external shoulder on the article adjacent an end thereof consisting of angularly related conical surfaces, and forcing said shoulder inwardly until one of said surfaces becomes substantially cylindrical and aligned with the exterior of the article and the other of said surfaces forms the end of a flange.

4. The process of forming a flange at an end of a tubular article comprising forming an external annular shoulder adjacent an end of the article and an internal annular groove corresponding therewith, and forcing the metal of the shoulder inwardly into alignment with the exterior surface of the article to form an annular flange.

5. The process of forming a flange at an end of a tubular article comprising forming an external annular shoulder on the article, cutting a groove on the interior surface of the article opposite the exterior shoulder, and drawing the article through a die to force the shoulder inwardly in the form of a flange.

6. The process of making a piston comprising casting a slug of metal, upsetting the same into the form of a piston having an external shoulder and drawing the piston to turn the metal of said shoulder inwardly in the form of an arcuate flange.

7. The process of making a piston comprising casting a slug of metal, upsetting the same into the form of a piston with an external annular shoulder at the open end, and drawing said piston against a removable core to turn the metal of said shoulder inwardly in the form of a fiange.

8. The process of making pistons comprising upsetting metal into the form of a piston having a head and a skirt and an external shoulder adjacent the open end of the skirt consisting of a pair of angularly related external surfaces disposed outwardly of the external surface of the skirt, and forcing said shoulder inwardly to arrange one of said angularly related surfaces into cylindrical formin continuation of the exterior surface of the skirt and to position the other of said angularly related surfaces substantially into a plane and extending inwardly over the open end of the skirt.

9. The process of forming a flange at the open end of the cylindrical skirt of a piston comprising forming an external shoulder on the skirt adjacent the open end thereof consisting of a pair of angularly related external surfaces, the first flaring outwardly from the skirt of the piston and the second extending at an angle from the first and applying a force to the interior of the piston at points spaced from said shoulder to force the piston through a drawing die in such a manner as to draw said first surface into cylindrical form in continuation of the skirt and to thereby carry said second surface into position extending inwardly over the open end of the skirt.

ALFRED ADOLF HANDLER. 

